Livio Valenti, 28

Cofounder of VaxessOne difficulty in getting vaccines to patients in the developing world is keeping them cold –the shots spoil if they're not refrigerated. Valenti's company, Vaxess, uses silk to stabilize vaccines so they can be stored and shipped. The company raised $4.5 million from Norwich Ventures and Angel Investor Jeffrey C. Walker. He is a fellow at Harvard's Center for Business and Government.